About Tholen
Tholen is a common asteroid. It has spectral type S and swings within 1.512 AU of the Sun at perihelion.
A Mars-crosser: its orbit reaches in far enough to cut clean across the path of Mars.
Common asteroid 18 EP
Tholen
Position computed live · sbdb
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Live ephemeris
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Score breakdown
· 4 badgesCommon 22 pts → Uncommon
- Has a proper name +8
- Mars-crosser +5
- Stony asteroid +4
- Asteroid +1
Total score 18
4 more points to reach Uncommon.
Badges
- Asteroid · +1
- Has a proper name · +8
- Mars-crosser · +5
- Stony asteroid · +4
Trivia
What it actually is
- Its orbit family. A Mars-crosser: its orbit reaches in far enough to cut clean across the path of Mars.
- Closest approach. At its nearest it comes within 1.51 AU of the Sun — inside the orbit of Mars.
- One lap. A single orbit around the Sun takes it about 3.7 years.
- How far it roams. Its orbit swings between 1.51 and 3.23 AU from the Sun.
Sense of scale
- Sense of scale. In everyday terms it is roughly 0.5× the height of Mount Everest.
By the numbers
- Size. Roughly 4 km across.
What's in a name
- Named. Notable enough to have earned a proper name, not just a catalogue number.
Properties
- albedo
- 0.341
- aphelion au
- 3.23
- designation
- 3255
- diameter km
- 4.023
- eccentricity
- 0.3628
- full name
- 3255 Tholen (1980 RA)
- h mag
- 13.56
- inclination
- 21.36
- mean motion deg day
- 0.2697
- moid au
- 0.668
- name
- Tholen
- named
- yes
- orbit class
- MCA
- perihelion au
- 1.512
- rotation period h
- 2.9463
- semi major au
- 2.372
- spec taxonomy
- S
- spect
- S
How to see it
Like any astronomical target, Tholen is best seen from a dark site away from city lights, and when it is above the horizon depends on your latitude and the time of year. Because it moves against the background stars, the live position panel on this page tracks where it is right now. The visibility panel above works out tonight's viewing window for your saved location.
Why Tholen is a common asteroid
Tholen scores 18 points on Spacedle's rarity scale, which places it in the common tier. Another 4 points would lift it into a rarer tier.
That score comes from 4 science badges — Asteroid, Has a proper name, Mars-crosser and Stony asteroid — each earned for a real, measurable property of the object. Rarity on Spacedle is never random: the more remarkable an object's astrophysics, the more badges it collects, the higher it scores, and the rarer it ranks.